Tree peony

Low-grade evening fever with no sweating, warm palms and soles, and a dry mouth, the picture of heat from yin deficiency

Heavy periods with dark clots and cramping in a woman who runs warm and flushes easily

Fixed lower abdominal pain with a palpable mass, prescribed alongside cinnamon twig and poria

Overview. Tree peony is a woody shrub of the peony family, native to the mountains of central and northern China and cultivated there for well over a thousand years for its flowers and its root bark. The medicine, mu dan pi, is the dried root bark of plants three to five years old, with the main supply from Anhui province. It is one of the standard heat-clearing, blood-cooling herbs of Chinese medicine and appears in many classical formulas, including Liu Wei Di Huang Wan and Gui Zhi Fu Ling Wan.

Clinical Notes. Mu dan pi does two things at once that few herbs manage: it cools heat in the blood and it moves blood. That makes it the herb for heat and stasis together, as in a woman with painful clotted periods who also flushes, sleeps hot and has a red tongue tip, or in the low evening fever without sweat that follows a long illness or accompanies yin deficiency.

Chinese Medicine Profile. Temperature: slightly cold. Taste: bitter, acrid. Channels: Heart, Liver, Kidney. Actions: Clears heat and cools the blood, for warm disease that has entered the blood level with rashes, nosebleed and vomiting of blood; Clears deficiency heat, especially the steaming-bone fever without sweating of yin deficiency; Invigorates blood and dispels stasis in amenorrhea, painful periods, abdominal masses and traumatic injury; Drains liver fire in headache, red eyes and flank pain; Reduces swelling and helps discharge pus in abscesses, including early intestinal abscess.

Conservation. Medicinal supply is from cultivation, mainly in Anhui and Shandong, and the species is not considered at risk; several wild tree peony relatives in China are protected and should not be wild-harvested.